Commentary for Genesis 43:9

והצגתיו לפניך AND SET HIM BEFORE THEE — for I will not bring him back to you dead but alive.

אנכי אערבנו…וחטאתי לך כל הימים "I will remain liable to you forever." The reason Yehudah said "forever" is explained by our sages in Bereshit Rabbah 91,10. The Hereafter is called "כל הימים," as it lasts forever.

וחטאתי לך, Yehudah did not really man that if he did not bring Binyamin back this would automatically be a sin in the objective meaning of the word. He meant that he would consider himself as a sinner against his father forever in the unlikely event that this would happen. He would guarantee his brother’s return under such conditions. These considerations prompted our sages in Makkot 11 to characterise Yehudah as placing himself in the position of a conditional outcast, מנודה, they derive the halachah that someone who places himself in such a state requires the court to annul his conditional vow, status. Needless to say that ostracising oneself from the Jewish community even conditionally is forbidden, and we have a tradition that the bones inside Yehudah’s coffin were rattling for the entire 40 years the Jewish people carried the coffins of the 12 founding leaders of the tribes with them through the desert. This stopped only at the request of Moses who asked mercy for Yehudah in his final blessing in Deuteronomy 33,7, וזאת 'ליהודה וגו